Surfers catching waves and mountain bikers pedaling through forests are used to the occasional low flying pelican or diving hawk. But these days, outdoor recreationists may find what's up in the air isn't a bird at all. It's a drone.

Last week top drone-makers, along with investors, regulators and inventors, gathered in California. They were in one of the most popular regions for outdoor activity in the U.S., along the state's Central Coast. They showed off their devices, heard about new uses for airborne robots and hit the waves and trails.

Drones Data X Conference Santa Cruz ran from May 1 to 3, and also featured experts. They explained how unmanned-aerial vehicles can map remote areas or rescue hikers or swimmers.

Federal regulators, who are still sorting out drone rules, were also on hand. They discussed updates on regulations about whether operators need to keep a drone within their line of sight, how high they can go and whether they can fly directly above a person.

"Drones are in a bit of their Wild West period right now. But in the future they'll be used to transport people, medicine, goods. Anything done on a highway will just as well be done by air," conference organizer Philip McNamara said.

Spending on unmanned aerial vehicles is projected to double over the next decade. It should grow from about $6.4 billion a year to $11.5 billion a year. That is according to industry analyst Teal Group.

McNamara said about 90 percent of the venture capital flowing toward drone technologies comes from the nation's high tech hub, Silicon Valley. It's about 30 miles from where the conference was held. Santa Cruz economic development director Bonnie Lipscomb said the city hoped some firms will like what they saw. The area includes sandy beaches and redwood forests.

Local mountain bike and kite surfing companies loaned gear and expertise to the conference.

Sergio Capozzi at the Society of Outdoor Recreation Professionals said there is both crossover and conflict between outdoor recreationists and drone enthusiasts.

"There is likely an appropriate time and place for drones in nature. The challenge comes in finding the right balance of when and where drones are appropriate," he said.

As prices go down and drone technology advances, park and wilderness visitors who want to use drones also need to make sure that everyone is having a safe and enjoyable experience, he said. He noted that, on the plus side, drones can be used to gather photos and videos. They would not be accessible otherwise.

"Sharing these experiences encourages others to seek out similar experiences, in particular on public landscapes," he said.

Richard Dolesh is a vice president at the National Recreation and Park Association. He said park managers aren't paying enough attention to increased drone use. He said people who are managing outdoor land and outdoor recreation aren't aware of what it's going to take to effectively manage drones.

Dolesh noted that national parks banned drones. Visitors complained about their noise.

"People travel long distances," he said, "for peace and solitude."

Critical thinking challenge: Why is spending on drones projected to double over the next decade?

I think that the development of drones are cool. They can be used to capture images and transport things such as medicine and goods. I think that drones might be able to help people with many things. The drones sound pretty fascinating to me and I hope they will be a great use.